1. Field of Invention
This invention relates generally to chemically-bonded anchors for fastening fixtures and other objects to masonry, and more particularly to an anchor sleeve and bolt assembly having a sleeve threadably received on the shank of the bolt, the assembly being insertable through a mounting hole in the fixture into a hole drilled in the masonry body to cause a charge of an uncured bonding agent deposited in the hole to spread into the space between the bank of the drilled hole and the sleeve whereby when the agent is cured, the sleeve is then anchored in the drilled hole and the fixture is fastened by the bolt to the masonry body.
2. Status of Prior Art
The term masonry refers to a construction of stone or similar material such as concrete and brick. The walls, ceiling and floors of many edifices are formed of masonry. In order, therefore, to fasten fixtures, machines, structural members or other objects to a masonry body, a masonry anchor is required for this purpose.
In the case of concrete or any other form of masonry, one cannot drill a hole therein and then tap this hole so that it can receive an anchor bolt, a threaded stud or other threaded mounting means to secure a fixture or other object to the face of the masonry. The nature of masonry is such that a tapping action to cut female threading into the bank of the hole cannot be effected, for this action will disintegrate the masonry material.
In order, therefore, to anchor a threaded mounting rod or stud in a hole drilled in masonry, the present practice is to use a curable chemical bonding agent for this purpose. The typical agent of this type has two flowable components, one a resinous bonding agent and the other, a hardener therefor. These two components, when stored, must be separated to prevent interaction therebetween. The resins may be phenol, vinyl, ester or epoxy based. Many bonding agents currently available have an accelerated curing time and set within 10 to 30 minutes to afford substantial holding power. The present invention is not concerned with the chemistry of these agents.
When using a typical chemical bonding agent in the drilled hole, a charge of the resinous component and sufficient hardener therefor is deposited in the hole, and a threaded mounting rod is then inserted in the hole and turned therein to intermix the two components of the chemical bonding agent.
When the resinous interfacial layer between the rod and the bank of the hole cures and rigidifies, it then bonds itself both to the rod and to the masonry, so that the rod is permanently anchored in the hole. In order now to secure a fixture to the masonry face, the fixture which has a mounting hole therein is placed over and onto the projecting stud and locked thereto by a washer and nut.
One serious practical drawback to this conventional technique is that should it become later necessary to remove the fixture so that it can be placed at another site on the masonry or for any other reason, one cannot, after withdrawing the fixture then also remove the mounting rod, for this rod is permanently anchored in place. And since the exposed end of the anchored rod projects above the masonry surface, it may interfere with the placement of a fixture at an adjacent site. In any event, this projection is unsightly and, in the case of a floor installation, represents a hazardous obstacle.
In order to provide an adhesive anchor for mounting an object on masonry, the patent to Ernst et al. U.S. Pat. No. 5,263,804 makes use of an internally threaded sleeve on whose upper end is snap-fitted a cap. The sleeve is inserted in a hole drilled in the masonry filled with an adhesive which spreads into the space between the bank of the hole and the sleeve. The cap is provided with a flange that is larger than the hole diameter, so that the sleeve may be seated in the hole at a desired depth. When the adhesive has set and the sleeve anchored, a threaded bolt is then inserted through the cap and turned into the internally-threaded sleeve to fasten an object to the masonry.
The advantage of the Ernst et al. anchor is that it is embedded in the masonry and does not project above as in the case of a chemically-anchored stud. Hence if one wishes to later remove the object from the masonry it is only necessary to unscrew the bolt from the anchor and nothing then remains other than the anchor which is flush with or below the masonry surface.
Disclosed in the Hibbs patent U.S. Pat. No. 4,652,193 is an adhesively secured anchor in the form of an internally-threaded shank having a chisel point. When the Hibbs anchor is driven into a hole drilled in masonry in which there is deposited a capsule containing an epoxy, the capsule is ruptured by the chisel to release the epoxy which then bonds the shank to the bank of the hole.
In order to drive the Hibbs shank, an installation tool is provided which is received in the internally-threaded bore of the shank, the tool being engaged by the chuck of an impact wrench. After the shank is properly anchored in the masonry, the tool is removed. Then in order to fasten a fixture or other object to the masonry, a threaded bolt is used which is inserted through a mounting hole in the fixture and turned into the anchored shank.
The problem with chemically-bonded anchors of the stud type which project above the surface of the masonry as well as with anchors of the type disclosed in the Ernst et al. and Hibbs patents in which the anchors are embedded within the masonry, is that in order to determine where holes are to be drilled in the masonry to accommodate the anchors, one must first put the fixture to be fastened to the masonry at its intended site.
The reason it is necessary to do so, is that the mounting holes in the fixture determine the location of the holes to be drilled in the masonry. After the hole locations are marked, the fixture must be again moved to permit holes to be drilled in the masonry body whose diameter is usually somewhat larger than the mounting holes in the fixture. After drilling a hole in the masonry, an uncured bonding resin is deposited in the drilled hole either by means of a glass capsule or a multi-barrelled cartridge which mixes the two components of the resin before it is deposited in the hole or as it is being deposited.
After the anchor is inserted in the masonry hole and the resin or other adhesive agent is cured and rigidified so that the anchor is then bonded in place, one must now return the fixture to be fastened to its intended site in the masonry body. If the anchor is of the stud type projecting out of the drilled hole, the fixture must be lifted over and onto the projecting stud. To complete the installation, a nut and washer is then received on each stud and the nut is tightened.
In the case of anchors which are embedded in the masonry body and do not project therefrom, it is only necessary to place the fixture so that its mounting holes are aligned with the internally-threaded anchors, and then insert bolts through the mounting holes of the fixture and turn the bolts into the anchors and tighten them to fasten the fixture to the masonry body.
These conventional procedures for fastening a fixture or other object to a masonry body are slow, time-consuming and costly. And where the object to be fastened is heavy and cumbersome as in the case of a large machine, it then becomes very difficult to carry out these known procedures.
One problem faced by the installer of an anchor into a hole drilled in masonry arises from the fact that when the hole has deposited therein a charge of an uncured bonding agent in which is inserted the anchor to be installed, the installer cannot then see into the hole. In order, therefore, to be sure that the charge of bonding agent he has deposited for its intended purpose is adequate, the installer depends on an overflow of the agent from the hole all around the anchor. This overflow indicates to the installer that the uncured bonding agent in the hole is properly spread about the inserted anchor. However, while this overflow of the uncured agent is necessary to a proper anchor installation procedure, it creates other problems, as will be later explained.
Also of background interest is the Kellison patent U.S. Pat. No. 4,642,964 which discloses a fastening system for chemically bonding an anchor in a hole drilled in masonry.